From: Francois Fleuret <francois@fleuret.org>
Date: Wed, 22 Aug 2012 18:19:44 +0000 (-0700)
Subject: Cosmetics.
X-Git-Url: https://www.fleuret.org/cgi-bin/gitweb/gitweb.cgi?p=mtp.git;a=commitdiff_plain;h=8df7c7e77366cb95e9e8e963af9319d9cbac1934

Cosmetics.
---

diff --git a/mtp_graph.cc b/mtp_graph.cc
index 5100c1d..ee6da31 100644
--- a/mtp_graph.cc
+++ b/mtp_graph.cc
@@ -28,6 +28,8 @@ public:
   int id, occupied;
   scalar_t length, work_length;
   Vertex *origin_vertex, *terminal_vertex;
+
+  // These are the links in the origin_vertex leaving edge list
   Edge *next, *pred;
 
   inline void revert();
@@ -38,7 +40,7 @@ public:
   int id, iteration;
   Edge *root_edge;
   scalar_t distance_from_source;
-  Edge *pred_edge;
+  Edge *best_pred_edge_to_source;
 
   Vertex();
   inline void add_edge(Edge *e);
@@ -80,7 +82,7 @@ void Vertex::del_edge(Edge *e) {
 
 void MTPGraph::print() {
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = edges + k;
+    Edge *e = _edges + k;
     cout << e->origin_vertex->id
          << " -> "
          << e->terminal_vertex->id
@@ -97,7 +99,7 @@ void MTPGraph::print_dot() {
   cout << "digraph {" << endl;
   cout << "  node[shape=circle];" << endl;
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = edges + k;
+    Edge *e = _edges + k;
     if(e->occupied) {
       cout << "  " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
            << " [style=bold,color=black,label=\"" << -e->length << "\"];" << endl;
@@ -111,48 +113,48 @@ void MTPGraph::print_dot() {
 
 MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
                    int *from, int *to,
-                   int src, int snk) {
+                   int source, int sink) {
   _nb_vertices = nb_vertices;
   _nb_edges = nb_edges;
 
-  edges = new Edge[_nb_edges];
-  vertices = new Vertex[_nb_vertices];
+  _edges = new Edge[_nb_edges];
+  _vertices = new Vertex[_nb_vertices];
   _front = new Vertex *[_nb_vertices];
   _new_front = new Vertex *[_nb_vertices];
 
-  _source = &vertices[src];
-  _sink = &vertices[snk];
+  _source = &_vertices[source];
+  _sink = &_vertices[sink];
 
   for(int v = 0; v < _nb_vertices; v++) {
-    vertices[v].id = v;
+    _vertices[v].id = v;
   }
 
   for(int e = 0; e < nb_edges; e++) {
-    vertices[from[e]].add_edge(&edges[e]);
-    edges[e].occupied = 0;
-    edges[e].id = e;
-    edges[e].origin_vertex = &vertices[from[e]];
-    edges[e].terminal_vertex = &vertices[to[e]];
+    _vertices[from[e]].add_edge(_edges + e);
+    _edges[e].occupied = 0;
+    _edges[e].id = e;
+    _edges[e].origin_vertex = _vertices + from[e];
+    _edges[e].terminal_vertex = _vertices + to[e];
   }
 
 }
 
 MTPGraph::~MTPGraph() {
-  delete[] vertices;
-  delete[] edges;
+  delete[] _vertices;
+  delete[] _edges;
   delete[] _front;
   delete[] _new_front;
 }
 
-void MTPGraph::initialize_work_lengths() {
+void MTPGraph::initialize_work_lengths_with_min() {
   scalar_t length_min = 0;
   for(int n = 0; n < _nb_vertices; n++) {
-    for(Edge *e = vertices[n].root_edge; e; e = e->next) {
+    for(Edge *e = _vertices[n].root_edge; e; e = e->next) {
       length_min = min(e->length, length_min);
     }
   }
   for(int n = 0; n < _nb_vertices; n++) {
-    for(Edge *e = vertices[n].root_edge; e; e = e->next) {
+    for(Edge *e = _vertices[n].root_edge; e; e = e->next) {
       e->work_length = e->length - length_min;
     }
   }
@@ -160,7 +162,7 @@ void MTPGraph::initialize_work_lengths() {
 
 void MTPGraph::update_work_lengths() {
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = edges + k;
+    Edge *e = _edges + k;
     e->work_length += e->terminal_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
   }
 }
@@ -170,7 +172,7 @@ void MTPGraph::force_positive_work_lengths() {
   scalar_t residual_error = 0.0;
 #endif
   for(int n = 0; n < _nb_vertices; n++) {
-    for(Edge *e = vertices[n].root_edge; e; e = e->next) {
+    for(Edge *e = _vertices[n].root_edge; e; e = e->next) {
       if(e->work_length < 0) {
 #ifdef VERBOSE
         residual_error -= e->work_length;
@@ -184,6 +186,8 @@ void MTPGraph::force_positive_work_lengths() {
 #endif
 }
 
+// This method does not change the edge occupation. It update
+// distance_from_source and best_pred_edge_to_source.
 void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
   Vertex **tmp_front;
   int tmp_front_size;
@@ -191,9 +195,9 @@ void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
   scalar_t d;
 
   for(int v = 0; v < _nb_vertices; v++) {
-    vertices[v].distance_from_source = FLT_MAX;
-    vertices[v].pred_edge = 0;
-    vertices[v].iteration = 0;
+    _vertices[v].distance_from_source = FLT_MAX;
+    _vertices[v].best_pred_edge_to_source = 0;
+    _vertices[v].iteration = 0;
   }
 
   int iteration = 0;
@@ -212,7 +216,7 @@ void MTPGraph::find_shortest_path(Vertex **_front, Vertex **_new_front) {
         tv = e->terminal_vertex;
         if(d < tv->distance_from_source) {
           tv->distance_from_source = d;
-          tv->pred_edge = e;
+          tv->best_pred_edge_to_source = e;
           if(tv->iteration < iteration) {
             _new_front[_new_front_size++] = tv;
             tv->iteration = iteration;
@@ -237,15 +241,17 @@ void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
   Edge *e;
 
   for(int e = 0; e < _nb_edges; e++) {
-    edges[e].length = lengths[e];
-    edges[e].work_length = edges[e].length;
+    _edges[e].length = lengths[e];
+    _edges[e].work_length = _edges[e].length;
   }
 
+  // We use one iteration of find_shortest_path simply to propagate
+  // the distance to make all the edge lengths positive.
   find_shortest_path(_front, _new_front);
   update_work_lengths();
 
   // #warning
-  // initialize_work_lengths();
+  // initialize_work_lengths_with_min();
 
   do {
     force_positive_work_lengths();
@@ -255,12 +261,12 @@ void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
     total_length = 0.0;
 
     // Do we reach the _sink?
-    if(_sink->pred_edge) {
+    if(_sink->best_pred_edge_to_source) {
       // If yes, compute the length of the best path
       v = _sink;
-      while(v->pred_edge) {
-        total_length += v->pred_edge->length;
-        v = v->pred_edge->origin_vertex;
+      while(v->best_pred_edge_to_source) {
+        total_length += v->best_pred_edge_to_source->length;
+        v = v->best_pred_edge_to_source->origin_vertex;
       }
       // If that length is negative
       if(total_length < 0.0) {
@@ -269,8 +275,8 @@ void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
 #endif
         // Invert all the edges along the best path
         v = _sink;
-        while(v->pred_edge) {
-          e = v->pred_edge;
+        while(v->best_pred_edge_to_source) {
+          e = v->best_pred_edge_to_source;
           v = e->origin_vertex;
           e->revert();
           e->occupied = 1 - e->occupied;
@@ -281,14 +287,8 @@ void MTPGraph::find_best_paths(scalar_t *lengths, int *result_edge_occupation) {
   } while(total_length < 0.0);
 
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = edges + k;
+    Edge *e = _edges + k;
     if(e->occupied) { e->revert(); }
-  }
-
-  for(int n = 0; n < _nb_vertices; n++) {
-    Vertex *v = &vertices[n];
-    for(Edge *e = v->root_edge; e; e = e->next) {
-      result_edge_occupation[e->id] = e->occupied;
-    }
+    result_edge_occupation[k] = e->occupied;
   }
 }
diff --git a/mtp_graph.h b/mtp_graph.h
index f12262e..7b0f57d 100644
--- a/mtp_graph.h
+++ b/mtp_graph.h
@@ -25,17 +25,20 @@ class Vertex;
 class Edge;
 
 class MTPGraph {
-  void initialize_work_lengths();
+  void initialize_work_lengths_with_min();
   void update_work_lengths();
   void force_positive_work_lengths();
   void find_shortest_path(Vertex **front, Vertex **new_front);
 
+  Vertex **_front, **_new_front;
+
   int _nb_vertices, _nb_edges;
   Vertex *_source, *_sink;
-  Vertex **_front, **_new_front;
+
+  Edge *_edges;
+  Vertex *_vertices;
+
 public:
-  Edge *edges;
-  Vertex *vertices;
 
   MTPGraph(int nb_vertices, int nb_edges, int *from, int *to,
            int source, int sink);